McLaren's new flagship supercar, dubbed a spiritual successor to the legendary F1, has been spied testing this week.

Reports out of Europe suggest the new car will utilise an enhanced version of the MP4-12C's 3.8 litre V8.

Britain's Car magazine reports that insiders at McLaren have confirmed that the massaged V8 will benefit from the addition of a KERS (kinetic energy recovery system) pack, boosting power to nearly 600kW.

Combined with its lightweight construction, the new car - known internally as the P12 - should be capable of sub-three second runs to the 100km/h mark.

The P12 is expected to make extensive use of carbon fibre, including the monocell tub that sits inside the company's current hero.

The new car will go even further however, using carbon fibre for its crash structures and body panels - where the MP4-12C currently uses aluminium.

"Whatever we do will be based on carbon," Sheriff says of the new car. "It will have performance and handling that's the best of its segment."

On the styling front, the P12 will reportedly go well beyond the relatively plain styling of the MP4-12C, with McLaren letting design boss Frank Stephenson off the leash - an advantage he didn't have with the 12C.

Described as "something out of the film I, Robot," the P12's body is expected to feature a subtle "double bubble" style to the canopy, and sharper Aventador-challenging lines across the body.